The dredging of harbors or other bodies of water for the purposes of deepening the channels to improve navigation or for the installation of large pipes or tunnels, requires that large quantities of accumulated slimy sludges or bay muds must be removed. These bay mud sludges contain very finely divided suspended solids that are difficult to separate from the aqueous suspensions and solidify. Such bay mud sludges, because of the finely divided physical state of the components such as clays, shells, and organic matter, are not usable as a landfill material because of their poor load supportive properties.
The mere settling of such sludges, even over an extended period of time, still does not provide a stable media.
The use of water quenched blast furnace slag in the solidification of some specific sludges has previously been proposed. In U.S. Pat. No. 3,920,795, for example, the addition of a granulated blast furnace slag, in an amount of between 1-20 percent, based on the solids content of a slurry, was made to aqueous calcium-containing inorganic sludges containing calcium sulfates and calcium sulfites, such as those resulting from sulfur dioxide removal from power plant combustion gases. Also, in U.S. Pat. No. 4,015,997, the addition of a granulated blast furnace slag, in an amount of between 2-50 percent, based on the solids content of a slurry, was made to aqueous coal processing sludges in a process for stabilizing the solids content thereof.
We have now discovered that a granulated blast furnace slag, when added to a basified slurry of bay mud sludge will stabilize the solids content thereof sufficient to provide load supportive properties.
It is an object of the present invention to provide a process for the stabilization of the solids content of bay mud sludges to convert the solids content thereof into a sedentary mass which evidences load supportive properties to an extent that they are usable as a load bearing landfill.
It is another object of the present invention to produce sedentary, load supportive masses from bay mud sludges which are far less prone to any effects to leaching, thus resulting in a decreased amount of contamination of ground water by soluble constituents in the resultant solidified and stabilized landfill.